Autonomous bird predation reduction device

ABSTRACT

A self-guided apparatus for repelling birds through various means of deterrence. The device comprises a chassis, a floatation assembly, a propulsion system, and a guidance and control system. The device may operate in either of at least two modes: passive and active. In the passive mode, the device traverses a predefined area, scaring birds away. In the active mode, the device surveys a designated area and, upon detection of birds, propels itself towards the birds and drives them away.

The benefit of the 14 Dec. 2001 filing date of U.S. provisional patentapplication Ser. No. 60/340,511 is claimed under 35 U.S.C. § 119(e) inthe United States, and is claimed under applicable treaties andconventions in all countries.

TECHNICAL FIELD

This invention pertains to a self-guided, autonomous vehicle designed toprovide an inexpensive method of reducing predation of aquatic organismsby birds.

BACKGROUND ART

Bird depredation of fish, crawfish, and shrimp in aquaculture pondsposes major problems. For example, pelicans can consume 1 to 3 lb (0.45to 1.36 kg) of fish per day, and may arrive with hundreds per flock.Cormorants, anhingas, herons, and egrets may also do significant damageto aquaculture ponds. It is estimated that one egret can eat ⅓ lb (0.15kg) of fish per day, while a great heron can eat ⅔ to ¾ lb (0.30 to 0.34kg) per day. See G. A. Littauer etal., “Control of Bird Predation atAquaculture Facilities: Strategies and Cost Estimates,” SouthernRegional Aquaculture Center, Publ. No. 402 (1997). This problem can beespecially troublesome in ponds that have just been stocked with youngfish.

M. D. Hoy et al., Eastern Wildlife Damage Control Conference, vol. 4,pp. 109–112 (1989), estimated that wading birds could cause profoundlosses during fall migration, up to $10,000 per week on bait fish farms.The Louisiana State University Ben Hur Aquaculture Facility in BatonRouge, La. recently experienced this problem with the white pelicanduring December 2000, when many fish were eaten and several ponds werecompletely de-stocked of fish.

A. R. Stickley et al., Eastern Wildlife Damage Control Conference, vol.4, pp. 105–108 (1989), estimated that in 1988 catfish losses due todouble-crested cormorants amounted to $3.3 million.

Currently, several different methods are employed to attempt to scarebirds from aquaculture ponds. One of the most common methods is the useof sonic cannons. Sonic cannons emit loud bursts of noise. However,birds eventually become accustomed to the noise emitted by soniccannons. Also, the loud “boom” produced by the sonic cannon can bedisturbing to surrounding communities, and typically causes birds tomigrate to other parts of the farm where the noise is more tolerable.See M. Bomford et al., “Sonic Deterrents in Animal Damage Control: AReview of Device Test and Effectiveness,” Wildlife Society Bulletin,vol. 18, pp. 411–422 (1990).

Poisons, scarecrows, and nets have also been used. However, thesemethods have several faults. For example, poisons are usually fatal tobirds and may cause casualties in non-target species. Scarecrows areeffective for short-term periods only, because birds typically adapt andbecome accustomed to them. Nets typically have a high initial cost andare not practical for large ponds (>5 acres/˜2 hectares).

An unfilled need exists for a cost-effective device and method foreffectively reducing bird predation of aquatic organisms over arelatively long period of time. The device should be environmentallyfriendly, harmless to birds, and capable of withstanding expectedenvironmental elements (e.g., water, wind, sun, and rain) and animalattacks. The device should also be able to endure biological challenges(e.g., wind, weeds, and slime), and should have some level ofintelligence to adapt to the evolving conduct of birds.

DISCLOSURE OF INVENTION

We have discovered a reliable and inexpensive device and method forrepelling birds through various means of deterrence. The device may beadapted to reduce predation by various bird species, and to operate indifferent environments. The predation reduction device comprises achassis, a floatation assembly, a propulsion system, and a guidance andcontrol system. The device may operate in either of at least two modes:passive and active. In the passive mode, the device traverses apredefined area, scaring birds away. In the active mode, the devicetraverses a surveyed area and, upon detection of birds, propels itselftowards the birds and drives them away.

Unlike prior devices and methods of reducing bird predation (e.g.,poisons, nets, remote control devices, etc.), the novel device isself-guided and employs harassing and intimidating tactics to repelpredatory birds. Optionally, a deterrent system (e.g., non-destructivewater cannon, scarecrow-type or other disguise, offensive-coloreddressing, etc.) is employed to assist in harassing and intimidating thebirds.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a front plan view of one embodiment of the predationreduction device.

FIG. 2 illustrates a perspective view of one embodiment of the predationreduction device with the solar panels removed.

FIG. 3 is an illustrative trajectory diagram depicting typical pathstraversed by one embodiment of the predation reduction device.

MODES FOR CARRYING OUT THE INVENTION

In the early stages of developing the present invention (unpublishedwork), a radio-controlled hobby boat (single-propeller drive source andbattery-powered) was adapted to operate as a bird predation reductiondevice. However, several problems were encountered. First, the boat wasunable to operate in an autonomous, self-guided manner. While the boatwas able to reach places that humans could not, continuous human controlwas necessary. Second, battery life tended to be less than half an hour,which was insufficient because bird predation typically occurs over anextended time period (an entire day). Third, the propeller easily becameentangled in weeds, which caused the boat to either slow or stop, andwhich increased the propeller's susceptibility to mechanical failure.Fourth, the boat chassis was not designed to carry additional equipment.Some of these problems were addressed by adding a large Styrofoam® (DowChemical Company, Midland, Mich.) platform to the boat chassis; however,the boat then became difficult to control.

In one embodiment, this invention provides a self-guided, autonomousdevice for driving birds away from a selected area. The basic designcomprises a chassis, a floatation assembly, a propulsion system, and aguidance and control system. The predation reduction device ispreferably solar powered and controlled by micro-controllers. Thepredation reduction device preferably operates in either or both of atleast two modes: active and passive. In the active mode, themicro-controllers communicate and function in conformity with anavigation system (e.g., machine vision system, global positioningsystem, sonar, etc.) and a collision prevention system to autonomouslynavigate the device around ponds and other waterways, eithercontinuously or upon detection of birds. When operating in the passivemode, the predation reduction device employs the collision preventionsystem only, allowing the device to move in a pre-determined pattern, orto perform a “random walk” type movement around a specified area. Uponmaking contact with an obstacle (e.g., shoreline, etc.), the devicestops, backs up, rotates between 0° to 360°, and then proceeds forwardagain. Alternatively, the device can be programmed to traverse apre-determined pattern.

This device has several advantages. First, costs are reduced compared toother predation reduction methods. The predation reduction device isvirtually self-sufficient, and thus reduces the need for humanintervention. Second, the predation reduction device is less harmful tobirds than many existing techniques because it employs harassing andintimidating tactics to drive birds away, instead of poisons or devicesthat are potentially lethal to birds. Third, the predation reductiondevice is energy-efficient and environmentally friendly. The devicepreferably relies on solar power. Fourth, the device can operateextremely quietly. Thus, the device may be employed at variouslocations, including aquaculture ponds located near residential areas.The device could save as much as hundreds of thousands of dollars peryear for farmers by reducing bird predation and environmental impacts.

FIG. 1 illustrates a front plan view of one embodiment of the predationreduction device 2. This embodiment comprised a chassis 4, a floatationassembly 6, a propulsion system, and a guidance and control system.Optionally, a deterrent system (e.g., non-destructive water cannon,scarecrow-type or other disguise, offensive-colored dressing, lights,sounds, etc.) can be added to the predation reduction device 2 to assistin harassing bird (not shown).

The floatation assembly 6 comprised two fixed floats 12 and two movablefloats 14. Fixed floats 12 were permanently mounted to chassis 4 onopposite sides of the predation reduction device 2 to provide buoyancy.Each fixed float 12 was enclosed in a casing to prevent damage fromfloating debris (e.g., sticks, weeds, etc.). Movable floats 14 wereadjustably attached to the sides of fixed floats 12 to balance thepredation reduction device 2 while in water. (The movable floats 14 wereslid forward or backward along the sides of the fixed floats 12 tobalance the predation reduction device 2 as equipment was added orremoved.) Both fixed and moveable floats, 12 and 14 respectively, weremade from a lightweight, buoyant material adapted to resistenvironmental degradation (e.g., degradation caused by sun, water, andbacteria) while providing sufficient buoyancy to keep predationreduction device 2 afloat, such as Styrofoam® (Dow Chemical Company,Midland, Mich.).

The propulsion system comprised a drive source and a motive source. Inthis embodiment, the drive source comprised two paddle wheels 16. Paddlewheels 16 were chosen because of their ability to traverse shallow waterfilled with debris, while allowing drive source placement above thewater line. (Paddle wheels 16 avoided entanglement with debris becausethe mechanical drive was located above the water line and the rotationalspeed was slower than propeller-type drive systems.) Paddle wheels 16provided operational speeds up to 7 mph (˜11 km/h), which was sufficientto discourage birds, and which incidentally caused additional aerationin the water. Paddle wheels 16 were individually mounted to chassis 4and centrally positioned between fixed floats 12 at a height sufficientto allow paddle wheels 16 to propel the predation reduction device 2.(Paddle wheels 16 were mounted between fixed floats 12 to avoidunnecessary contact with debris. Fixed floats 12 were adapted to allowapproximately 1.5 in (˜3.80 cm) of the surface area of each paddle wheel16 into the water.) Each paddle wheel 16 independently rotated forwardand backward, providing a means for the predation reduction device 2 tobe maneuvered to almost any position. For example, to propel thepredation reduction device 2 forward or backward, paddle wheels 16 wererotated evenly in the same direction. To change the direction in whichthe predation reduction device 2 was traveling, paddle wheels 16 wererotated in opposite directions.

Each paddle wheel 16 was driven by a motive source capable of providingtorque and shaft speed sufficient to accelerate and propel the predationreduction device 2 effectively, such as a Pittman® electric motor, modelGM712-31 (Harleysville, Pa.). Electric motors 18 were operated by anelectric power source. Electric motors 18 were mounted a safe distancefrom the water surface and adapted to be attached to paddle wheels 16.Electric motors 18 were chosen for ease of maintenance and the abilityto be recharged in an environmentally friendly manner (e.g., solarpower).

In this embodiment, the electric power source comprised solar powerpanels 20 mounted on top of the predation reduction device 2. Solarpower panels 20 provided a means for energizing electrical systems, andalso provided overhead cover for the guidance and control system. Solarpower panels 20 provided sufficient power to energize the propulsionsystem and guidance and control system during daytime operations, andsufficient power to charge batteries for limited nighttime operations.

FIG. 2 illustrates a perspective view of one embodiment of the predationreduction device. In this embodiment, the guidance and control systemcomprised an electronic system 22, a collision prevention system, and anavigation system. In this embodiment, the electronic system 22 furthercomprised a micro-controller system (not shown) having motor controllerscapable of supporting program languages and of communicating with thenavigation system, such as Lego® Robotic Control X systems (RCX) (LegoSystems, Enfield, Conn.), or Basic II Stamp semiconductor chips(Parallax, Inc., Rocklin, Calif.). The micro-controller system operatedby processing guidance information received from either a collisionprevention system (mechanical proximity feelers, optical, image, sonar,radar, doppler radar shoreline indicators, etc.) or a navigation system(machine vision, global positioning, local area navigation, etc.), orboth. The micro-controller system independently controlled each electricmotor 18 by using the guidance information to determine the directionand action needed by the paddle wheels to move the boat. Themicro-controller system sent signals to the motor-controllers to actuateelectric motors 18. (Motor controllers are not always necessary foroperation of the vehicle. In some instances, relays or similar devicescan be employed instead.) Programming in software supplied by themicro-controller manufacturer provided a means for the motor controllersto communicate with the navigation system, and to apply variable powerto electric motors 18.

A collision prevention system was used to prevent the predationreduction device 2 from colliding with obstacles. In one embodiment, thecollision prevention system comprised four, ⅜ inch (˜0.9 cm) diameterfiberglass poles (proximity feelers) 28, each mounted on a corner of thepredation reduction device 2 and connected to triggering mechanisms 23operable in moist environments, such as sealed mechanical magneticswitches, Radio Shack Cat. No. 49-497 (Tandy Corporation, Fort Worth,Tex.). The collision prevention system communicated with the electronicsystem 22, and provided a means to operate the predation reductiondevice 2 in a passive mode. The collision prevention system alsoprevented the occurrence of collisions when operating the predationreduction device 2 in an active mode. Optionally, a string 25 or wirecan be attached between proximity feelers 28, thereby forming adetection zone capable of detecting objects, such as the shoreline,drain pipes, and rocks. Also, a position-indicating system, such asglobal positioning system, Model “310” or “330” (Magellan Corporation,San Dimas, Calif.), may be employed to track or control the movement ofthe predation reduction device 2. (not shown)

In one embodiment, to facilitate the identification and pursuit ofbirds, the navigation system employed a machine vision system 30, suchas Lego® Mindstorms Vision Command (Lego Systems, Enfield, Conn.). Datafrom machine vision system 30 was transmitted to a data processingsystem (not shown) removably mounted underneath solar power panels 20(not shown) to facilitate an active functional mode, such as a Compaq®Presario® laptop computer, model 275-0005A (Compaq, Houston, Tex.). (Thesolar power panels 20 also provided overhead cover for the dataprocessing system.) The data processing system processed data gatheredby machine vision system 30. Optionally, a deterrent system (e.g.,non-destructive water cannon, a rotating laser system, etc.) can beemployed to harass and intimidate birds once detected. The rotatinglaser system scares away birds by creating a moving beam (e.g., line,dot, or strip) on the shore, or on an object sticking out of the water,startling birds as it passes. The laser power range is adapted to avoidadversely affecting the sight of birds. The rotating beam creates alight burst that startles birds and other animals observing thepredation reduction device 2.

FIG. 3 is a trajectory diagram depicting typical paths traversed by oneembodiment of the predation reduction device 2. In this embodiment, thepredation reduction device 2, operating in passive mode, employedproximity sensors 28 and triggering mechanisms 23 to perform “randomwalk-type” movements around a pond. Upon detecting the shoreline, thepredation reduction device 2 backed away from the shoreline, rotatedbetween 0° to 360°, and headed in a different direction.

EXAMPLE 1

Construction of the Prototype

The chassis 4 was made from aluminum sheet metal and bar stock. Thefixed and moveable floats, 12 and 14, respectively, were fabricated fromStyrofoam®, and protected from mechanical damage by 16-gauge aluminum.The chassis 4 contained two fixed floats 12 (volume=660 in³ (˜10.8 L))and two moveable floats 14 (volume=315 in³ (˜5.2 L)) attached to theside of each fixed float 12 to provide additional buoyancy and balance.The chassis 4 provided approximately 50 lb (˜16 kg) total buoyancy. Thetotal weight of the predation reduction device 2 was between 30–40 lb(˜13–18 kg), depending upon the embodiment being operated.

Paddle wheels 16 were constructed from riveted sheet aluminum. Paddlewheels 16 were mounted on each side of the predation reduction device 2and attached to two 12V Pittman®, Model GM712–31, electric motors 18.Electric motors 18 were connected to paddle wheels 16 by a gear drivewith a 1:16 gear ratio, which allowed electric motors 18 to bepositioned above fixed floats 12 at a safe distance from the watersurface.

After determining that electric motors 18 required approximately 0.3 Aeach, during both forward and backward movement, and about 0.6 A eachduring directional changes, three solar power panels 20, ModelSKU#41144, (LY, Inc., China) (single amorphous silicon cell solar powerpanels, 12 V dc, 350 mA, 5 Watt), were mounted above paddle wheels 16;these panels also sheltered the data processing system directlyunderneath. Solar power panels 20 provided 1.3 amperes at 12 V dc inbright sunlight, which provided enough energy to operate the predationreduction device 2 and to charge the batteries. (An additional solarpanel was later added to increase the total current to approximately 1.8amps at 12 V dc, in direct sunlight.) Two 12 V batteries (Elks®, Model1245, 12 V dc, 5.0 Ah) were used to store power for limited nighttimeoperations.

In one embodiment, the electronic system 22 comprised a single chipmicro-controller. Two different micro-controllers were used duringinitial testing. The first micro-controller was a Lego® Mindstorms RCX.The Mindstorms RCX micro-controller contained three built-in motorcontrollers (0.5 A each at 9 V dc) and three digital (or switch) inputs.A 9 V regulator was used to power the micro-controller from the 12 V dcbatteries. The second micro-controller was a Basic II Stampsemiconductor chip. This chip had 2K bytes of electrical memory, a 20 Hzclock rate (4000 instructions per second), and 16 input/output lines. AnH-bridge relay system and motor controllers were operated with theMindstorms RCX micro-controller to control the paddle wheel motors(since the Mindstorms RCX micro-controller was 9 V dc and main batterieswere 12 V dc). The relays used in the H-bridge were Radio Shack Model275-0005A. Solutions Cubed, Motor Mind B motor controllers were employedwith the Basic II Stamp semiconductor chip to operate the paddle wheels16. This arrangement allowed speed control of electric motors 18 usingserial transmissions from the Basis II Stamp micro-controller to theSolutions Cubed, Motor Mind B motor controller, which used pulse widthmodulation. (Basic II Stamp semiconductor chips have the advantage ofapplying variable rate power to electric motors 18, using serialtransmissions from the Basic II Stamp semiconductor chip and Pulse WidthModulation.) These chips were rated at 2 A continuous current output,with a built-in heat sink. All electronics were protected from theenvironment using Tupperware® containers or Ziplock®bags. The MindstormsRCX micro-controller and the Basic Stamp II controller were used tocontrol separately the direction and movement of electric motors 18 forsteering and propulsion of the predation reduction device 2. Bycontrast, when the Vision Command was used, the Mindstorms RCXmicro-controller relayed steering commands from the Vision Commandsoftware and the Compaq® Presario® laptop computer to the Basic StampController (which controlled the paddle wheel motors). The Basic StampII controller used computer language, basic algorithms and specialsubroutines to control motor direction and speed when either theproximity feelers 28 were actuated, or when steering commands were sentfrom the Mindstorms RCX micro-controller and the Vision Command. Theseroutines included special “slow spin-down to a stop” and “slow spin-upfrom a stop” functions to reduce mechanical wear (i.e., a kind ofelectronic clutch). In cases where the Mindstorms RCX was used, the samecommands were developed using object oriented programming language forthe Lego® systems.

The collision prevention system was employed to prevent collisions withobjects. In facilitate this system, ⅜ inch (˜0.9 cm) diameter fiberglasspoles (proximity feelers 28) from a mobile TV antenna, Radio Shack Cat.No. 15-1609 (Tandy Corporation, Fort Worth, Tex.), were mounted on eachcorner, using either a specially bent 4 inch to 6 inch (˜10 cm to 15 cm)standard light tee hinge (National, Sterling, Ill.), which triggered theRadio Shack Cat. No. 49-497 (Tandy Corporation, Fort Worth, Tex.)magnetic switches upon collision with the shore, or another objecthaving sufficient inertia. (Magnetic switches 23 were employed becausethey were sealed and completely waterproof.) A string 25 was run betweenproximity feelers 28 to detect objects such as drain pipes and rocks. Ahandheld, waterproof global positioning system (Magellan CorporationModel “310” or “330”) was also added to provide positional information.This system transferred data with the micro-controller through a serialcable using standard NEMA (National Marine Electronics Association) 0183code. (This system was not used with the Lego® Mindstorms RCX, becauseserial transmission inputs were not available for it.)

EXAMPLE 2

Predation Reduction Tests

To confirm that the prototype predation reduction device 2 was effectivein repelling predatory birds, tests were conducted using variousnavigation methods. In one embodiment, a navigation method usedproximity feelers 28 to detect the shoreline and then turn the predationreduction device 2. Using this method, the device 2 performed a “randomwalk” type movement around the pond as the shoreline was encountered.The predation reduction device 2 backed up for 6 seconds to move awayfrom the shoreline, and then turned for 6 seconds to perform a 0° to360° turn. (Micro-controllers, software and either relays or transistordrivers were adapted and employed to accomplish this “random walk-type”movement.) These functions (i.e., traversing the pond, backing up, andturning) also scared the birds away from the pond and the shoreline.Initial testing was conducted at the Louisiana State University Ben HurAquaculture Center in Baton Rouge, La.

Another navigation method comprised a global positioning system andprogramming algorithms to follow coordinates programmed into the globalpositioning system. Another navigation method employed machine visionsystem 30 to identify birds. Data from machine vision system 30 wastransmitted to the data processing system. The data processing systemused a pre-determined grid pattern that divided the image of the pondinto sections, and then trained each section to sense light, motion, orcolor to detect birds. (The image of the pond was photographed by acamera mounted to chassis 4, on the front side of the predationreduction device 2). Motion was detected by comparing subsequent framesfrom the camera (30 images/sec) to detect differences, such as newoccurrences of birds in the frames. Color was detected by “training” thedata processing system to recognize the color of a bird (from either amodel of the bird or a captured image of a real bird), and then trainingthe data processing system to scan subsequent frames for detection ofthe color in a certain percentage of the image area (a percentage thatcould be adjusted). Brightness can also be used to find birds,especially if an infrared camera is employed to acquire images. Thisapproach is especially suitable for work at night. These detectionmethods can be used separately or they may be combined to detect birds.Image detection was programmed using the Lego® Mindstorms Vision Commandsystem, which contains an object oriented programming language fordetection schemes such as these. Navigation routines were alsoprogrammed into the Basic II Stamp semiconductor chip to control turningtowards the detected birds. Turning data was transmitted to the BasicStamp II micro-controller using a 5 volt regulator chip, connectedbetween the motor driver output ports of the Lego® Mindstorms RCX.andthe micro-controller input pins. Software routines were programmed intothe Basic II Stamp chip to control turning towards birds detected indifferent parts of the image. In addition, a windshield washer (ModelP50, Poberk, Brownsville, Tex.) was attached to the Lego® MindstormsVision Command system using a 9V dc, single pole, double throw relay,Radio Shack Cat. No. 275-005A (Tandy Corporation, Fort Worth, Tex.) tosquirt water at a bird (in front of the device 2) when the machinevision system 30 indicated the bird was in the center of the image,approximately 10 to 20 feet away. (This distance can be increased withhigher pressure/flow rate water streams and improved image processingequipment). Currently, the water cannon in the prototype delivers astream of water at 0.25 liters/sec. In some instances, the system alsosquirted birds on the shore. These operations allowed the predationreduction device 2 to detect, turn, and chase and harass birds.

The global positioning system and the Basic II Stamp semiconductor chiphave also been programmed to create an imaginary boundary diagram of thepond. However, at the time this application was filed, the “imaginaryboundary” system had not yet been tested. It is envisioned that thissystem would create a box or other shaped area in which the predationreduction device 2 would operate using global positioning systemcoordinates. When the predation reduction device 2 nears the boundary ofthe preset area (indicated by the global positioning systemcoordinates), it would change directions, based on either the randomdirection algorithm of the predation reduction device 2 or a magneticcompass. This system could be employed when multiple boats are used topatrol separate areas of a large pond.

Also, adual stageDoppler radar sensor (Bulldog Security Inc.,Wintersville, Ohio) was tested to detect birds close to the predationreduction device 2. This system could be employed to detect objectslocated near (within 4–5 ft (˜1.2–1.5 m)) of the predation reductiondevice 2. This system was also able to detect the shoreline and otherobjects of sufficient mass. Passive infrared sensors are currently beingtested to detect birds as well.

The “characteristic distance” is defined to be the typical or averagedistance within which the predation reduction device must approach abird in order to cause the bird to leave the vicinity of the device. The“characteristic distance” may vary by type of bird, time of day, time ofyear, weather, hunger or other physical state of the bird, thecharacteristics of the particular device (e.g., presence of watercannon, color, alligator or other predator-like disguise, etc.), and thebird's degree of familiarity with the device or similar devices. Thecharacteristic distance in prototype tests has typically been on theorder of 10 to 30 ft (˜3 to 9 m).

EXAMPLE 3

Alternative Embodiment

In an alternative embodiment, a docking station (not shown) can beemployed to automatically recharge the batteries on the predationreduction device 2. Optionally, batteries with a low charge may bereplaced with fully charged batteries. In this embodiment, the dockingstation comprises a hub platform and output terminal posts. The hubplatform has V-shaped guides which extend outwardly to engage thepredation reduction device 2. (The docking station can be positioned onthe water or moored to the shore-line.)

Once a low battery level is detected, the navigation system processesguidance information received from either the collision preventionsystem (e.g., mechanical proximity feelers, sensory bumper guards, etc.)or the navigation system (machine vision system, differential globalpositioning system, etc.) to locate and engage the docking station. Themachine vision system may be programmed to detect a homing signal (e.g.,blinking light) mounted on the docking station. When using thedifferential global positioning system, the navigation system isprovided real time positioning information to locate the dockingstation. An input terminal post capable of receiving externally providedpower and distributing power to the batteries is mounted in front of thepredation reduction device 2.

Once the predation reduction device 2 locates the docking station, thepaddle wheels 16 propel it towards the docking station. Upon engagement,the V-shaped guides lead the predation reduction device 2 to a positionwhere the input terminal post contacts one of the output terminal posts,allowing 12V DC, 110V AC, or 220V AC to be used to recharge thebatteries. (Electrical power maybe provided to the docking station byseveral means, including batteries and a solar power array, anelectrical cable connected to an electrical outlet located on the shore,or a gasoline powered electrical generator.) If the predation reductiondevice 2 initially fails to engage the V-shaped docking port, thecollision prevention system (e.g., mechanical proximity feelers, sensorybumper guards, etc.) causes the boat to back up and try again.

When charging is completed, a signal is transmitted to themicro-controller system reversing the propulsion of the predationreduction device 2 until it completely disengages from the dockingstation. The predation reduction device 2 then performs its previousfunctions until another recharging is needed.

RESULTS

Reduction in Bird Predation

Aquatic predatory birds were not present in large numbers during initialtesting, but limited testing was performed on occasional birds (e.g.,herons, egrets, geese, and cormorants) that landed in protected ponds.During these tests, birds, were either driven away from the pond or didnot fly onto the pond in which the device was located. During one test,an egret watched the predation reduction device 2, and then flew awaywhen the predation reduction device 2 made a turning maneuver near it.In another test, the predation reduction device 2 was placed on a pondand allowed to operate all day. A flock of geese that had usuallyfrequented the pond did not visit the pond while the predation reductiondevice 2 was present. The birds seemed “hazed” by the predationreduction device 2. Additional tests were conducted on egrets andcormorants, during times of peak bird predation. These tests involvedputting up to 2 boats on the surface of a 1 acre pond (˜0.4 hectares)stocked with catfish fingerlings and recording the bird populations witha time-lapse recorder. These tests were run for three days with a boaton the pond, and then three days without a boat. Replications were donefor several months between November and December of 2001. Review of therecordings indicated that the boat reduced bird populations byapproximately 75%, and in some instances up to 100%.

The machine vision system 30 did encounter some initial problems. Thesystem worked well in the laboratory, but had a brightness problem withthe intense sunlight found outside; however, the brightness problem maybe solved by using a tinted lens, a different camera, or adjusting thecamera software. Also, the machine vision system seemed to have problemscalibrating to white colors, including sun glare, which appears to be aproblem inherent to the Lego® Vision Command software. These problemscan be solved by adding software routines to provide a more positiveidentification of the birds using fuzzy logic, neural networks, maximumlikelihood classifier routines and multiple pieces of information fromthe image or other sensors, such as color, shape, and heat signaturecombined.

Deterrence System

Testing of the non-destructive water cannon was effective in scaringbirds, but in preliminary tests the predation reduction device 2 wasnever in close enough proximity to actually spray a bird. Lasers arebeing investigated for longer range “scaring” of birds.

Electrical Power Source

The solar power panels 20 worked effectively throughout the day,providing enough energy to operate the predation reduction device 2.Measurements indicated that the predation reduction device 2 consumedapproximately 0.6 to 0.8 A, while solar power panels 20 produced over1.5 A on sunny days. In cloudy conditions, solar power panels 20supplied enough power to maintain traversing operations for a reducedtime (4–6 hours). Nighttime testing has not yet been performed, but itis believed that the prototype predation reduction device 2 will run atleast several hours on stored battery power. A future version of thepredation reduction device 2 may include batteries with greater storingcapacity.

Guidance and Control System

The collision prevention system proved to be essentially 100% effective.The system allowed the predation reduction device 2 to back up androtate between 0° to 360°. Proximity feelers 28 and mechanical magneticsensors 23 provided a means for the predation reduction device 2 torandomly traverse essentially the whole pond. During initial testing,the predation reduction device 2 traversed the entire surface area(i.e., within about 20 ft (˜6.1 m) of 90% of the pond surface) of a 1.5acre (˜0.6 hectares) pond, with 2 to 5 mph (˜3 to 8 km/h) winds, inabout 30 minutes. In addition, during a long duration test, the boateffectively “lived” on the pond without getting caught or snagging on anobject. The device can be protected from aerators by placing aprotective device around the aerators, such as an anchored plastictubing ring that sits approximately 1 ft (˜0.3 m) below the surface.

Paddle wheels 16 effectively propelled the predation reduction device 2at a high speed (5 mph) (˜8 km/h), while maintaining low power draw fromelectrical motors 18. Also, paddle wheels 16 were not jammed or cloggedwith weeds. (The predation reduction device 2 has not to date beentested in water containing high trash volumes.) Paddle wheel 16 speedswere slow, and water friction was kept to a minimum.

Some problems were initially encountered with the gear drive. The Lego®Mindstorms RCX micro-controller and H-relays (which had a sudden“on/off” effect) caused excessive wear in the gear drive and excessiveshock loading on shafts and set screws during directional changes. Thisproblem was eliminated by using the Basic II Stamp micro-controller,which was programmed to ramp down the motor speed before a directionalchange, an effect that could also be implemented in the Lego® RCXprogramming, i.e., a type of electronic clutch.

In some instances, winds in excess of 10 mph (˜16 km/h) caused thepredation reduction device 2 to drift, even while power was applied.Several design parameters were changed to reduce wind effects. First,the boat was streamlined. Solar power panels 20 were placed horizontallyto reduce wind effects. Floats 12 and 14 were trimmed in size to lowerthe floatation level of the predation reduction device 2, minimizing thesurface area of floats 12 and 14 above the surface of the water. Arudder was added to aid in maintaining direction during windy periods.(not shown)

The Lego® RCX micro-controller contained a limited number ofinput/output lines when used with the machine vision system 30, but itstill effectively controlled the propulsion system, including theproximity feelers 28 and the navigation system. The Basic II Stampsemiconductor chip appeared more reliable than the Lego® Mindstorms RCXmicro-controller.

The global positioning system was accurate to within about 5 to 6 ft(˜1.5 to 1.8 m); however, in some situations, positioning measurementsdeviated as much as 30 ft (˜9 km/h)(with selective availability turnedoff). This error is not critical in a large pond (>5 acres/˜2 hectares),but could cause some problems in a small pond (<1 acre/˜0.4 hectares).For this reason, the proximity feeler system and the “random walk” typemethods were solely used for navigation. In the future, the globalpositioning system may be used to guide the predation reduction device 2between different ponds using, for example, an amphibious-design vehiclecapable of traversing land and water through the use of multiple paddlewheels 16.

Future testing will explore the interaction between birds and theirenvironment. Birds quickly adapt to “standard” signals, such as theregular movement of equipment or even of other animals. Suddenmovements, such as changes in direction or rotation of the predationreduction device 2, seem to startle birds. Active deterrence systems,such as lasers or non-destructive water cannons, seem to reinforce birdintimidation. The addition of highly visible patterns (e.g., large eyes,alligator silhouettes, etc.) may also aid in improving the effectivenessof the deterrence system.

It is believed that this device or similar devices could be used forother in-field environmental and biological engineering applications.Possible uses include remote measurement of water quality parameters,crop scouting, site-specific environmental monitoring for various crops,pest predation reduction applications, and possibly crop harvest.Similar systems might be used in wild ecosystems to monitorenvironmental quality. The addition of a radio modem system to allowdata to be sent back to a field station is another future development.

Future embodiments of the predation reduction device 2 will include thefollowing: (1) an improved frame design (e.g., a frame built of eitherplastic, wood or other floatation materials), and mechanical componentsthat generate more power which would allow the predation reductiondevice 2 to be propelled faster; (2) an improved machine vision system30 will employ classifier schemes that will help recognize birds usingfaster algorithms and a combination of information input sources (e.g.,color, object size and texture, heat, etc.) to better identify birds;(3) either a swivel drive (U-joint, etc.) or a direct drive coupling toconnect electric motors 18 to paddle wheels 16; (4) adifferentially-corrected global positioning system may be used to obtainmore accurate readings (although not necessary in the currentembodiment); (5) multiple paddle wheels 18 capable of traversing leveesmay be added to the predation reduction device 2 to allow it to movebetween ponds; and (5) a docking station capable of recharging batterieson the predation reduction device 2, to allow all-night operations andfaster speeds if solar panels 20 were removed or reduced.

The complete disclosures of all references cited in this specificationare hereby incorporated by reference. Also incorporated by reference isthe complete disclosure of the inventors own work: S. Hall et al.,“Development of an Autonomous Bird Predation Reduction Device,” An ASAEMeeting Presentation, Paper No. 01-3131 (Presented Jul. 30-Aug. 1,2001). In the event of an otherwise irreconcilable conflict, however,the present specification shall control.

1. A device for traversing a water body and for reducing the number ofbirds in the vicinity of the water body, said device comprising: (a) oneor more floats having sufficient buoyancy to maintain a portion of saiddevice above the surface of the water body; (b) an electrically-poweredpropulsion system adapted to transport said device across the surface ofthe water body, without the need for continuous monitoring or input froma human; (c) an electrically-powered collision prevention system todetect potential collisions before collisions occur, and to cause saidpropulsion system to alter the direction of transport of said device toavoid at least some detected potential collisions before collisionsoccur; all without the need for continuous monitoring or input from ahuman; (d) an electrically-powered navigation system adapted to causesaid propulsion system to periodically transport the device within thecharacteristic distance of at least 75% of the surface of the water bodyat least once every two hours; and (e) a power source to supplyelectrical power, directly or indirectly, to said propulsion system, tosaid collision prevention system, and to said navigation system;whereby: (f) the transport of the device on the water body causes areduction in the number of birds in the vicinity of the water body ascompared to the number of birds that would be present in the absence ofthe transport of the device.
 2. A device as recited in claim 1, whereinsaid device is adapted to operate in an active and a passive mode;wherein in the active mode, said device autonomously traverses asurveyed area of the water body either continuously or upon detection ofat least one bird; and wherein in the passive mode, said devicetraverses the water body without regard to the location of any birds. 3.A device as recited in claim 1, wherein when said collision preventionsystem detects a potential collision said device is adapted to stop,back up, rotate between 0° and 360°, and then proceed forward, whileoperating either in a passive or active mode.
 4. A device as recited inclaim 1, wherein said propulsion system comprises a drive source and amotive source; wherein said drive source comprises at least two paddlewheels; and wherein said motive source comprises at least one electricmotor to activate each paddle wheel.
 5. A device as recited in claim 4,wherein said motive source operate said paddle wheels independently topropel and steer said device.
 6. A device as recited in claim 1, whereinsaid collision prevention system comprises proximity feelers pivotallymounted on said device and attached to a triggering mechanism.
 7. Adevice as recited in claim 6, wherein said triggering mechanismcomprises a magnetic switch.
 8. A device as recited in claim 1, whereinsaid navigation system is capable of identifying birds and guiding saiddevice in the direction of said birds.
 9. A device as recited in claim1, wherein said power source comprises solar panels.
 10. A device asrecited in claim 9, wherein said power source additionally comprises oneor more batteries adapted to store energy from said solar panels.
 11. Adevice as recited in claim 1, wherein said electrically-powerednavigation system is adapted to cause the propulsion system toperiodically transport the device within the characteristic distance of90% of the surface of the water body at least once every thirty minutes.12. A collection comprising a plurality of devices for traversing awater body and for reducing the number of birds in the vicinity of thewater body, said device comprising: (a) one or more floats havingsufficient buoyancy to maintain a portion of said devices above thesurface of the water body; (b) an electrically-powered propulsion systemadapted to transport said devices across the surface of the water body,without the need for continuous monitoring or input from a human; (c) anelectrically-powered collision prevention system to detect potentialcollisions before collisions occur, and to cause said propulsion systemto alter the direction of transport of said devices to avoid at leastsome detected potential collisions before collisions occur; all withoutthe need for continuous monitoring or input from a human; (d) anelectrically powered navigation system adapted to cause the propulsionsystem to transport said devices across the water body, wherein at leastone of said devices in said collection is periodically transportedwithin the characteristic distance of at least 75% of the surface of thewater body at least once every two hours; and (e) a power source tosupply electrical power, directly or indirectly, to said propulsionsystem, to said collision prevention system, and to said navigationsystem; whereby: (f) the transport of said devices on the water bodycauses a reduction in the number of birds in the vicinity of the waterbody as compared to the number of birds that would be present in theabsence of the transport of said devices.
 13. A collection as recited inclaim 12, wherein said devices are adapted to operate in an active and apassive mode; wherein in the active mode, said devices autonomouslytraverse a surveyed area of the water body either continuously or upondetection of at least one bird; and wherein in the passive mode, saiddevices traverse the water body without regard to the location of anybirds.
 14. A collection as recited in claim 12, wherein when saidcollision prevention system detects a potential collision said devicesare adapted to stop, back up, rotate between 0° and 360°, and thenproceed forward, while operating either in a passive or active mode. 15.A collection as recited in claim 12, wherein said propulsion systemcomprises a drive source and a motive source; wherein said drive sourcecomprises at least two paddle wheels; and wherein said motive sourcecomprises at least one electric motor to activate each paddle wheel. 16.A collection as recited in claim 15, wherein said motive source operatesaid paddle wheels independently to propel and steer said devices.
 17. Acollection as recited in claim 12, wherein said collision preventionsystem comprises proximity feelers pivotally mounted on said devices andattached to a triggering mechanism.
 18. A collection as recited in claim17, wherein said triggering mechanism comprises a magnetic switch.
 19. Acollection as recited in claim 12, wherein said navigation system iscapable of identifying birds and guiding said devices in the directionof said birds.
 20. A collection as recited in claim 12, wherein saidpower source comprises solar panels.
 21. A collection as recited inclaim 20, wherein said power source additionally comprises one or morebatteries adapted to store energy from said solar panels.
 22. Acollection as recited in claim 12, wherein said electrically-powerednavigation system is adapted to cause the propulsion system toperiodically transport said devices within the characteristic distanceof 90% of the surface of the water body at least once every thirtyminutes.
 23. A device for traversing a surveyed area and for reducingthe number of birds in the vicinity of the surveyed area, said devicecomprising: (a) one or more floats having sufficient buoyancy tomaintain a portion of said device above the surface of a water body whenoperating the device in water; (b) an electrically-powered propulsionsystem adapted to transport said device across the surface of thesurveyed area, without the need for continuous monitoring or input froma human; (c) an electrically-powered collision prevention system todetect potential collisions before collisions occur, and to cause saidpropulsion system to alter the direction of transport of said device toavoid at least some detected potential collisions before collisionsoccur; all without the need for continuous monitoring or input from ahuman; (d) an electrically-powered navigation system adapted to causethe propulsion system to periodically transport the device within thecharacteristic distance of at least 75% of the surface of the surveyedarea at least once every two hours; and (e) a power source to supplyelectrical power, directly or indirectly, to said propulsion system, tosaid collision prevention system, and to said navigation system;whereby: (f) the transport of the device on the surface of the surveyedarea causes a reduction in the number of birds in the vicinity of thesurveyed area as compared to the number of birds that would be presentin the absence of the transport of the device.
 24. A device as recitedin claim 23, wherein said device is adapted to operate in an active anda passive mode; wherein in the active mode, said device autonomouslytraverses a surveyed area either continuously or upon detection of atleast one bird; and wherein in the passive mode, said device traversesthe surveyed area without regard to the location of any birds.
 25. Adevice as recited in claim 23, wherein when said collision preventionsystem detects a potential collision said device is adapted to stop,back up, rotate between 0° and 360°, and then proceed forward, whileoperating either a passive or active mode.
 26. A device as recited inclaim 23, wherein said propulsion system comprises a drive source and amotive source; wherein said drive source comprises at least two paddlewheels; and wherein said motive source comprises at least one electricmotor to activate each paddle wheel.
 27. A device as recited in claim26, wherein said motive source operate said paddle wheels independentlyto propel and steer said device.
 28. A device as recited in claim 23,wherein said collision prevention system comprises proximity feelerspivotally mounted on said device and attached to a triggering mechanism.29. A device as recited in claim 28, wherein said triggering mechanismcomprises a magnetic switch.
 30. A device as recited in claim 23,wherein said navigation system is capable of identifying birds andguiding said device in the direction of said birds.
 31. A device asrecited in claim 23, wherein said power source comprises solar panels.32. A device as recited in claim 23, wherein said power source is adocking station adapted to recharge said device.
 33. A device as recitedin claim 31, wherein said power source additionally comprises one ormore batteries adapted to store energy.
 34. A device as recited in claim32, wherein said power source additionally comprises one or morebatteries adapted to store energy.
 35. A device as recited in claim 23,wherein said electrically-powered navigation system is adapted to causethe propulsion system to periodically transport the device within thecharacteristic distance of 90% of the surface of the surveyed area atleast once every thirty minutes.